American Journal of Analytical Chemistry, 2013, 4, 229-237 http://dx.doi.org/10.4236/ajac.2013.45029 Published Online May 2013 (http://www.scirp.org/journal/ajac) Volatile Substances in Polymer Toys Made from Butadiene and Styrene Yutaka Abe*, Miku Yamaguchi, Motoh Mutsuga, Hiroshi Akiyama, Yoko Kawamura Division of Food Additives, National Institute of Health Sciences, Tokyo, Japan Email: *[email protected] Received March 25, 2013; revised April 25, 2013; accepted May 1, 2013 Copyright © 2013 Yutaka Abe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT The residual levels and migration behavior of volatile substances were detected using HS-GC/MS for acrylonitrile-bu- tadiene-styrene copolymer (ABS) toys, thermoplastic elastomer toys, and rubber toys made from 1,3-butadiene and sty- rene found on the Japanese market. The maximum residual level of these volatile substances was 2600 μg/g of styrene in ABS toys. In particular, the levels of known carcinogens 1,3-butadiene, benzene, and acrylonitrile are 5.3, 2.5 and 55 μg/g, which are much lower than the EU limit of 0.1%. Furthermore, some volatile substances migrated from ABS toys into water in amounts of 3 - 40 ng/mL. Thermoplastic elastomer toys and rubber toys contained these volatile sub- stances at significantly lower levels than ABS toys. Keywords: Volatile Substance; Toy; Acrylonitrile-Butadiene-Styrene Copolymer (ABS); Thermoplastic Elastomer; Rubber 1. Introduction nomers remain or not. Among these volatile substances, some have been Various plastic materials are used in toys for babies such identified as potentially carcinogenic or toxic substances. as teethers, rattles, dolls, toy vehicles, educational toys, and animal toys. Among these toy materials, copolymers The International Agency of Research on Cancer (IARC) made from 1,3-butadiene and styrene as the main mono- has classified 1,3-butadiene as a group 1 carcinogen (car- mers are widely used. The acrylonitrile-butadiene-styrene cinogenic to humans); styrene, acrylonitrile, ethylben- copolymer (ABS) is used as hard materials for the bodies zene, and 4-viniyl-1-cyclohexene as group 2B carcino- of vehicle toys, the shafts of baby teethers and rattles, and gens (possibly carcinogenic to humans); and toluene as a so on. On the other hand, thermoplastic elastomers such group 3 carcinogen (not classifiable as to its carcino- as styrene-butadiene-styrene block copolymer (SBS), sty- genicity to humans) [9]. Meanwhile, the EU has classi- rene-ethylene-butadiene-styrene block copolymer (SEBS), fied 1,3-butadiene as a category 1A carcinogen and as a and rubbers such as styrene-butadiene rubber (SBR) are category 1B mutagen and has classified acrylonitrile as a used as the soft materials of baby teethers or rattle bodies. category 1B carcinogen [10]. ABS is manufactured from 1,3-butadiene, styrene, and Of particular concern is that these substances could be acrylonitrile as the main monomers with some substances. taken orally from chewing toys for babies. Therefore, to Therefore, unreacted monomers such as 1,3-butadiene ensure the safety of these toys, it is essential to survey [1-3], styrene [4-6], or acrylonitrile [3,4,7] are usually the residual levels and migration behavior of the volatile detected in ABS products. Furthermore, other volatile substances in these copolymer toys. However, to the best substances such as toluene, ethylbenzene, isopropylben- of our knowledge, only two analyses of the residual le- zene, propylbenzene [4,6], and 4-vinyl-1-cyclohexene [3, vels of these volatile substances in ABS toys have been 8] derived from the solvent, impurities, or side reactions published [3,6]. Moreover, there has been no report of are also detected. Furthermore, thermoplastic elastomers the residual levels of these volatile substances in thermo- such as SBS, SEBS, and styrene rubbers such as SBR are plastic elastomer toys and rubber toys made from 1,3- also manufactured from 1,3-butadiene and styrene with butadiene and styrene, nor has there been any report on other substances, and it is unclear whether unreacted mo- their migration. *Corresponding author. In this study, we identified the residual substances and Copyright © 2013 SciRes. AJAC 230 Y. ABE ET AL. determined their residual levels and migration behavior (DCB, special grade, >98%) was purchased from Tokyo in ABS toys, thermoplastic elastomer toys, and rubber Kasei Kogyo Co., Ltd. (Tokyo, Japan). toys on the Japanese market using a headspace gas chro- The standards and internal standards used in this study matograph/mass spectrometer (HS-GC/MS). are shown in Table 1. The mixed volatile substance stand- ard stock solutions were prepared at concentrations of 0.5 2. Experimental - 50,000 μg/mL in DMA, DCB, and methanol. The mix- ed internal standard stock solutions were prepared as fol- 2.1. Samples lows. For the analysis of residual levels of volatile sub- Seventy-three toy samples comprising fifty-nine ABS stances in ABS toys, 1,2-butadiene, isobutyronitrile, and toys, twelve thermoplastic elastomer toys, and two sty- p-diethylbenzene were mixed in DMA at 100, 10,000, rene-butadiene rubber toys were collected from the Ja- and 1000 μg/mL. For the analysis of the residual levels panese market in 2011. Two ABS sheets (sheets 1 and 2) of volatile substances in thermoplastic elastomer toys and were provided for the recovery tests by The Japan Hygi- rubber toys, 1,2-butadiene, isobutyronitrile, and 1,3,5-tri- enic Olefin and Styrene Plastics Association. methylbenzene were mixed in DCB at 100, 10,000, and 1000 μg/mL. For the analysis of migration levels of vola- 2.2. Reagents and Standard Solutions tile substances, 1,2-butadiene, isobutyronitrile, and p-die- thylbenzene were mixed in methanol at 100, 500, and N,N-Dimethylacetamide (DMA, HPLC grade) was pur- 1000 μg/mL. All standard stock solutions and internal chased from Sigma-Aldrich Japan (Tokyo, Japan). Me- standard stock solutions were kept in storage bottles with thanol (HPLC grade) was purchased from Merck (Merck a tightly sealed cap (Kanto Chemical Co., Inc., Tokyo, KGaA, Darmstadt, Germany), and p-dichlorobenzene Japan) and stored at −20˚C. Table 1. Standards and internal standards. Purity Retention Monitored ion (m/z) Chemical name CAS No. Supplier*1 (%) time (min) Quantifying ion Qualifying ion Standard 1,3-Butadiene*2 106-99-0 >95 A 6.1 54 39, 53 Acrylonitrile*2 107-13-1 >99.8 B 10.7 53 52 Benzene 71-43-2 >99 C 13.2 78 52 Methylisobutyrate 547-63-7 >95 D 13.6 43 71, 41 Methylmethacrylate 80-62-6 >99.8 E 14.1 69 41 1-Octene 111-66-0 >95 D 14.9 55 70 Toluene 108-88-3 >99.5 F 15.0 91 92 4-Vinyl-1-cyclohexene 100-40-3 >95 D 15.8 79 54, 91 Ethylbenzene 100-41-4 >99 D 16.3 91 106 p-Xylene 106-42-3 >98 D 16.4 91 106 Styrene 100-42-5 >99 D 16.8 104 78 Isopropylbenzene 98-82-8 >98 D 17.0 105 120, 91 Propylbenzene 103-65-1 >97 D 17.4 91 102, 105 α-Methylstyrene 98-83-9 >98 D 17.7 118 117, 91 Internal standard 1,2-Butadiene*2 590-19-2 >95 A 7.2 54 53, 39 Isobutyronitrile 78-67-1 >99 E 13.1 68 42 1,3,5-Trimethylbenzene 108-67-8 >97 E 17.4 105 120 p-Diethylbenzene 25340-17-4 >99 D 18.3 105 117, 120 *1A: Hayashi Pure Chemical Ind., Ltd.; B: AccuStandard; C: Kokusan Chemical Co., Ltd.; D: Wako pure Chemical Industries, Ltd.; E: Tokyo Chemical Indus- *2 try Co., Ltd.; F: Aldrich Chemical Co., Inc.; Methanol solution (1000 µg/mL). Copyright © 2013 SciRes. AJAC Y. ABE ET AL. 231 2.3. Headspace (HS)-GC/MS Conditions 2.4.2. Determination of Amount of Migration of Volatile Substances The HS sampler (HP7694, Agilent Technologies, CA, Each test sample was cut to 1 cm × 1 cm and then placed USA) conditions are shown in Table 2, and the GC/MS into a 20-mL HS vial, after which 4 mL of water and 5 (6890 GC and 5973 MSD, Agilent Technologies) condi- μL of the mixed internal standard stock solution in tions are as follows. The column was a DB-624 (0.25 methanol were added. After all solutions were added, the mm i.d. × 60 m, 1.4 μm film thickness [Agilent Tech- vial was immediately tightly sealed and then set into the nologies]). The oven temperature was initially 40˚C for 7 HS sampler. The vial was heated at 40˚C for 30 min, and min and was then increased at 20˚C/min to 250˚C, which then the HS gas was analyzed using GC/MS. was held for 5 min. The injection temperature was 200˚C, and the transfer-line temperature was 250˚C. The helium 2.5. Calibration Curve and Limit of carrier gas was flowed at 1.2 mL/min (constant speed). A Quantification split injection mode was used with a ratio of 10:1, and the ion source voltage was 70 eV. Finally, a selected ion To construct the calibration curves for the determination monitoring (SIM) mode was used, and the monitored of the residual levels and amounts of migration of vola- ions are given in Table 1. tile substances, standard solutions were prepared as fol- lows. 2.4. Sample Preparation For the determination of residual levels of volatile substances in ABS toys, 5 - 50 μL quantities of the mixed 2.4.1.